The invention concerns a method for authenticating different objects or substances to be identified comprising at least two phases: during an initial phase, selecting a plurality of chemical markers, assigning to and incorporating in each of the objects or substances a combination of markers, establishing an identification and/or authentication code (blocks 2, 11), storing in memory data or code for identifying and/or authenticating all the objects or substances and annex data; during an identification and/or authentication phase: a spectrophotometric analysis so as to determine a specific scanned code of the presence or absence of the markers (blocks 3, 4), identifying the object or the substance by comparing the scanned code and the identification and/or authentication codes (block 6). The invention is particularly applicable to fighting against counterfeiting, to automatic sorting, and the like.